A general disease and parasite survey of commercially important fishes of the Free State

English: Inland aquaculture has started to receive increased interest in South Africa and indeed the Free State Province. This is a means to diversify agriculture production, the creation of jobs and contributing towards food security. Sharptooth catfish/baber Clarias gariepinus, common carp Cyprinus carpio and rainbow trout Oncorhyncus mykiss have been identified as commercially viable species in the Free State, although the latter species was not collected during the current study. Parasitological data was collected from the above mentioned host species as well as other species of interest from impoundments in the Free State. Under aquaculture conditions susceptible hosts are usually in close proximity, for intensive culture thereby facilitating the transmission and establishment of parasites and diseases. As such, parasites and diseases of fish are regarded as significant constraints to the development of inland aquaculture in the province. The present study was a disease and parasite survey of commercially important fishes of the Free State Province. Herein we qualitatively assess the risk to sustainable development of a fresh water aquaculture industry based on parasitic data collected from field surveys in the Free State Province carried out over a period of two years 2013 and 2014 and parasitic data collected from the Agricultural Technology Demonstration Centre in Gariep Dam during 2016. The taxa collected included; the alien parasitic crustaceans Lernaea cyprinacea and Argulus japonicus; monogeneans Quadriacanthus aegypticus, Dactylogyrus sp 1 and Dactylogyrus sp 2.; the alien cestode, Schyzocotyle acheilognathi; peritrich ciliophorans Trichodina centrostrigeata, Tripartiella lechridens as well as the alien species Trichodina nigra and Trichodinella epizootica. Although some of the above species have been shown to cause mass mortalities of fish hosts both in the wild and in aquaculture, during the current study mortalities as a direct result of parasite infestations/infections were not encountered. The study found that parasites and diseases can indeed be constraints to aquaculture development in the province, coupled with factors such as access to markets, profits and economic value of the species being farmed.